Pressure sensitive copying paper

ABSTRACT

An excellent pressure sensitive copying paper is provided by applying a color former certain encapsuled 6-di lower alkyl amino-naphthalfluoran compounds to either a single sheet or to the upper leaf of a pressure sensitive paper. The color former is soluble in aromatic solvents and also has excellent light fastness.

United States Patent Seki et a1. 5] Feb. 4, 1975 [54] PRESSURE SENSITIVECOPYING PAPER 3,506,471 4/1970 Kimura et a1. 117/362 3,514.311 5/1970 Kt t'l 117/362 [75] Inventors: Hlmmlts Sek'; Ken! Yamamml 3,649,6493/1972 260/335 x both ofOsaka-Japan 3.691.203 9/1972 Koya et a1 117/368[73] Assignee: Yarnamoto Kaguku Gosei Kabushiki FQREIGN PATENTS ORAPPUCATIONS Osaka Japan 1.018,?93 2/1966 Great Britain 2611/336 1 1 ppN913101585 Chemical Abstracts. Vol. 24. 1930 page 3.7130.

' Related US. Application Data P E Th J H b t J 1 rzmary xamzner omas erer r. [62] D1v1s10n of Ser. No. 208,415, Dec. 15, 1971. Attorney g orFirm Armstrong Nikaido & [30] Foreign Application Priority Data WagnerDec. 15,1970 Japan 45-112053 ABSTRACT [52] U.S. c1 ll7/36.2, 117/368,260/335 An excellent Pressure Sensitive py P p is P [51] Int. Cl. B4lcl/06 Vided pp a color former Certain encapsuled [58] Field of Search117/362, 36.8; 260/335 lower alkyl amino-naphthalfluoran compounds toeither a single sheet or to the upper leaf of a pressure [56] R f en Cid sensitive paper. The color former is soluble in aro- UNITED STATESPATENTS matic solvents and also has excellent light fastnessr 3,442,9085/1969 Orita et a1 260/335 8 Claims, N0 Drawings PRESSURE SENSITIVECOPYING PAPER BACKGROUND OF THE INVENTION Basically, pressure sensitivecopying paper consists of two sheets of paper, the lower surface of theupper leaf having applied thereto minute capsules containing a colorreactive achromatic substance (hereinafter called a color former)dissolved in a low volatile solvent and the upper surface of the lowerleaf being coated with a solid acid, such as acid clay, zeolite,bentonite, attapulgite & phenolic compounds, etc. When the lower surfaceof the upper leaf and the upper surface of the lower leaf are puttogether and pressure is applied to the upper surface of the upper leafby handwriting or typing, the capsules under pressure are broken and thecolor former contained therein is adsorbed by the solid acid on theupper surface of the lower leaf to develop a color, thus providing acopy.

There is also a type of pressure sensitive copying paper having amechanism to develop a color when a regional pressure is exerted upon asheet of paper holding capsules, which contain a color former, and asolid acid on or within it. However, such type is quite similar to thefirst-mentioned pressure sensitive copying paper (consisting of twosheets of paper, an upper and lower leaf) with respect to the mechanismof developing a color, and thus the same color former can be used forboth types. And any of the above-mentioned facts belongs to theprior-known arts.

Conventionally, a number of compounds have been known to be useful asthe color former, such as lactones, i.e., crystal violet lactone andmalachite green lactone; thiazine compounds, i.e., benzoylleucomethylene blue; and other leucoauramine and spiropyran compounds,and others. They have made it possible to manufacture various kinds ofproducts which develop such colors ranging from yellow and red to blue,green and black. However, the light resistance after development ofcolor, particularly when inorganic substances such as acid clay, Silton(manufactured and soled by Mizusawa Chemical Company Ltd), etc. are usedas the solid acid, has been unsatisfactory, so that it has been hopedfor to fine out some solution for this defect. It is only benzoylleucomethylene blue that shows a satisfactory light resistance, but itdevelops a color at a very low speed. Therefore it can not be used forpractical purposes, unless it is mixed with some other color formerwhich develops a color at a higher speed. Even this mixed use offersmuch inconvenience from a practical point of view, since benzoylleucomethylene blue, which develops a blue color, imposes a restrictionon the variety.

SUMMARY In accordance with the invention, an excellent pressuresensitive copying paper can be obtained by using a new and novel colorformer which distinguish himself in the speed of color development, andthe shade of the color, the simplicity of the manufacturing method andthe light resistance of the color developed.

The color former used in the present invention can be represented by thefollowing general formula (I).

That is to say, we have found that the fluoran compounds which have anaphthalene ring in the structure of the lactone ring can become a colorformer with an excellent light resistance and that they can be readilysynthesized by the process shown by the following reaction formula.

COOII l DETAILED DESCRIPTION The following are typical examples of thenovel color former.

3-methyl-6-ethylamino-7-methylnaphthalfluoran (Ill) -NII CzHs 3 crn@ Kaa) l (111) is light brown crystal obtained by condensing 8-(4-methyl-2-hydroxybenzoyl)-a-naphthoic acid (which is obtained bycondensing naphthalic anhydride and methacresol through Friedel-Craftsreaction) and 2-ethylaminoparacresol in sulfuric acid and having amelting point of 1 19 to 120C. 1t develops an orange color, reactingwith a solid acid, and has a very good light resistance after developinginto the color.

(III) (1V) is light reddish brown crystal obtained by condensing8-(5-methyl-2'-hydroxy-benzoyl)-anaphthoic acid (which is obtained bycondensing naphthalic anhydride and paracresol through Friedel-Craftsreaction) and 2-ethylaminoparacresol in sulfuric acid and having amelting point of 187 to 192C. lt develops a yellowish orange colorreacting with a solid acid, and has an excellent light resistance afterdeveloping into the color.

2-chloro-3-methyl-6-ethylamino-7-methylnaphthal- (V) is light reddishbrown crystal obtained by condensing8-(4-methyl-5'-chloro-2-hydroxybenzoyl)-anaphthoic acid (which isobtained by condensing naph- 'thalic anhydride and 2-chloromethacresolthrough Friedel-Crafts reaction) and 2 -ethylaminoparacresol in sulfuricacid and having a melting point of 160- 1 65C. It develops a yellowishorange color reacting with a solid acid, and has a remarkably excellentlight resistance after developing into the color.

3-chloro-6-ethylamino-7-methylnaphthalfluoran (V1) 0 Cl Wavnmn (V1) islight reddish brown crystal obtained by condensing8-(4-chloro-2-hydroxy-benzoyl)-a-naphthoic acid (which is obtained bycondensing naphthalic anhydride and methachlorophenol throughFriedel-Crafts reaction) and Z-ethylaminoparacresol in sulfuric acid andhaving a melting point of 167 to 170C. 1t develops a yellowish orangecolor reacting with a solid acid, and has an excellent light resistanceafter developing into the color.

l,2-benzo-6-ethylamino-7-methylnaphthalfluoran (V11) is light ocherouscrystal obtained by condensing 8-(2'-hydroxynaphthoyl)-a-naphthoic acid(which is obtained by condensing naphthalic anhydride and B-naphtholthrough Friedel-Crafts reaction) and 2- ethylaminoparacresol in sulfuricacid and having a melting point of 210 to 214C. 1t develops a black orblackish green color, reacting with a solid acid, and has an excellentlight resistance after developing into the color.

3-methyl-6-diethylaminonaphthalfluoran (V111) (V111) is light browncrystal obtained by condensing 8-(4-methyl-2-hydroxybenzoyl)-a-naphthoic acid (See the description about(111) and methadiethylaminophenol in sulfuric acid and having a meltingpoint of 170 to 174C. 1t develops a reddish purple color, reacting witha solid acid, and has an excellent light resistance after developinginto the color.

Now the present invention if further illustrated by the followingexamples.

EXAMPLE 1.

6 0 g of gelatin and 60 g of gum arabic were dissolved in 50 ml of waterof 40C. On the other hand, 1.2 g of3-methyl--ethylamino-7-methylnaphthalfluoran (Ill) was dissolved in 120g of diphenyl chloride, and then this solution was added to theabovementioned aqueous solution of gelatin and gum arabic and perfectlydispersed into an emulsion by a homomixer. Water of 50C was added untilits volume became 2,000 ml in total, followed by 90 ml of percent aceticacid. While stirring, water of 50C was further added until the totalweight became 4 kg, and the stirring was continued for a period ofanhour. While still stirring, the solution was cooled down to below 10Cwith ice water, and 10 percent caustic soda was added until a pH of 9was reached and gradually returned to room temperature. The product wasapplied onto the lower surface of the upper leaf and dried. On the otherhand, a solid acid such as acid clay or phenolic compounds, was appliedonto the upper surface of the lower leaf.

When copying was carried out with the upper and lower leaves thusprepared, an orange image developed, which showed an excellent lightresistance.

EXAMPLE 2 1.2 g of 2-methyl-6-ethylamino-7-methylnaphthalfluoran (IV)was dissolved in 120 g of diphenyl chloride, then the solution thusprepared was treated in the same way as in Example 1 to obtain anaqueous dispersion of minute capsules. This was sprayed and dried into apowder of minute capsules, which was mixed with and dispersed in a 4percent xylene solution of pphenylphenol formaldehyde condensate. Andthis dispersed solution was applied onto a sheet of paper and dried.When a regional pressure was exerted on this sheet of paper, itimmediately developed a yellowish orange image, which showed anexcellent light resistance.

EXAMPLE 3.

1.2 g of 2-chloro-3-methyl-6-ethylamino-7-methylnaphthalfluoran (V) wasdissolved in 120 g of diphenyl chloride. By treating this solution inthe same way as in Example 1, an aqueous dispersion of minute capsuleswas obtained. This was mixed with 8 g of fine power of p-phenylphenolformaldehyde condensate to disperse the latter therein, and further 40 gof pulp was added thereto. Then the dispersion was diluted with wateruntil the final solid content became 0.5 percent. Then the product wasrun onto a Fourdrinier screen to be made into a sheet of paper. whenthis sheet of paper was subjected to a regional pressure, it immediatelydeveloped a reddish orange image, which showed an excellent lightresistance.

EXAMPLE 4.

60 g of gelatin and 60 g/gum arabic were dissolved in /of 50 ml of waterof 40C. On the other hand, 1.0 g of3-chloro-7-acetylaminonaphthalfluoran (V111) was dissolved in 120 g ofdiphenyl chloride, and then this solution was added to theabove-mentioned aqueous solution of gelatin and gum arabic and perfectlydispersed into an emulsion by a homo-mixer. Water of 50C was added untilits volume became 2,000 ml in total, followed by 90 ml of 10 percentacetic acid. While stirring, water of 50C was further added until thetotal weight became 4 kg, and the stirring was continued for a period ofan hour. While still stirring, the solution was reached and graduallyreturned to room temperature. The product was applied onto the lowersurface of the upper leaf and dried. On the other hand. a solid acidsuch as acid clay or phenolic compounds. was applied onto the uppersurface of the lower leaf.

When copying was carried out with the upper and lower leaves thusprepared, an bluish green image developed, which showed an excellentlight resistance.

formaldehyde condensate. And this dispersed solution was applied onto asheet of paper and dried. When a cooled down to below 10C with icewater, and 10 per-" cent caustic soda was added until a pH of 9 wasregional pressure was exerted on this sheet of paper, it

developed a bluish green image, which showed an excellent lightresistance.

EXAMPLE 6.

1.0 g of 3-chloro-7-acetylaminonaphthalfluoran (Vlll) was dissolved inI20 g of diphenyl chloride. By treating this solution in the same way asin Example 4. an aqueous dispersion of minute capsules was obtained.This was mixed with 8 g of fine powder of pphenylphenol formaldehydecondensate to disperse the latter therein, and further 40 g of pulp wasadded thereto. Then the dispersion was diluted with water until thefinal solid content became 0.5 percent. Then the product was run onto aFourdrinier screen to be made into a sheet of paper. When this sheet ofpaper was subjected to a regional pressure, it developed a bluish greenimage, which showed an excellent light resistance.

Although an aromatic solvent was used as a solvent in the foregoingexamples, the same pressure sensitive copying paper can be obtainedwithout problem with the use of other aromatic solvent. Other aromaticsolvents of low volatility include lower alkyl diphenyls, such asmethyl-, ethyland propyl diphenyl, and higher alkyl benzenes, such asdodecyl-, decyland octyl benzene, having a boiling point of above C. Ifthe boiling point of the solvent is at least 150C, it has sufficient lowvolatility according to the invention.

The solid acid functions as an electron acceptive adsorbent. In lieu ofthose used in the previous examples zeolite, bentonite, attapulgite andSilton (manufactured and saled by Mizusawa Chemical Company) can be usedwith excellent results.

What is claimed is:

1. In a pressure sensitive copying paper, a paper sheet having appliedthereto at least one fluoran compound of the formula:

wherein R R and R are members selected from the group consisting ofhydrogen, methyl and halogen; R and R are both hydrogen or one of R andR is hydrogen, and the other is methyl or ethyl; and R is a memberselected from the group consisting of hydrogen, methyl, amino andacetylamino; also R and R when joined together represent a hydrocarbonresidue which forms a benzene ring.

2. Pressure sensitive copying paper according to claim 1 comprising anupper leaf having said fluoran compound applied thereto, said compoundbeing dissolved in a solvent of low volatility and the resultingsolution being packed in minute capsules, and lower leaf having appliedthereto a solid acid.

3. Pressure sensitive copying paper according to claim 1 in which asingle sheet of paper has applied thereto said fluoran compound, saidcompound being dissolved in a solvent of low volatility and theresulting

2. Pressure sensitive copying paper according to claim 1 comprising anupper leaf having said fluoran compound applied thereto, said compoundbeing dissolved in a solvent of low volatility and the resultingsolution being packed in minute capsules, and lower leaf having appliedthereto a solid acid.
 3. Pressure sensitive copying paper according toclaim 1 in which a single sheet of paper has applied thereto sAidfluoran compound, said compound being dissolved in a solvent of lowvolatility and the resulting solution being packed in minute capsules,and a solid acid.
 4. Pressure sensitive copying paper according to claim1 wherein the fluoran compound is3-methyl-6-ethylamino-7-methylnaphthalfluoran.
 5. Pressure sensitivecopying paper according to claim 1 wherein the fluoran compound is2-methyl-6-ethylamino-7-methylnaphthalfluoran.
 6. Pressure sensitivecopying paper according to claim 1 wherein the fluoran compound is2-chloro-3-methyl-6-ethylamino-7-methylnaphthalfluoran.
 7. Pressuresensitive copying paper according to claim 1 wherein the fluorancompound is 3-chloro-6-ethylamino-7-methylnaphthalfluoran.
 8. Pressuresensitive copying paper according to claim 1 wherein the fluorancompound is 1,2-benzo-6-ethylamino-7-methylnaphthalfluoran.